The importance of an adequate supply of methionine to the diet of both animals and humans has long been reported in literature. Methionine is an essential amino acid needed in the building of body protein. Adequate dietary intake of methionine for swine, cattle and poultry has been known for some time to be of importance. An adequate level of methionine in the diets of swine, poultry and cattle has been shown to be important for healthy growth of the animals. Animal diets are often supplemented with DL-methionine to assure the adequacies of the sulfur amino acids content.
The DL-alpha-hydroxy analog of methionine (MHA) has been used as a substitute for DL-methionine, particularly in poultry diets. The efficacy of the alpha-hydroxy analog and its calcium salt were compared with that of DL-methionine in a chick bioassay. These studies indicated that the Ca salt of alpha-hydroxy analog is superior to the free acid and has approximately equivalent efficacy to the DL-methionine.
The synthesis of DL-alpha-hydroxy-gamma-methyl-mercapto butyric acid (the alpha-hydroxy analog of methionine) and its calcium salt were described by Blake et al. in U.S. Pat. Nos. 2,745,745 and 2,938,053 issued in May 15, 1956 and May 24, 1960, respectively. The zinc salt of alpha-hydroxy analog was also disclosed in the literature. The previously disclosed calcium and zinc salts are the diacid salts in which two molecules of the alpha-hydroxy acid are neutralized with one ion of the divalent cations of zinc or calcium. These salts are very sparingly soluble in water. The low water solubility of the salts probably decreases the bioavailability of these products as feed supplements and a water soluble compound is likely to be more bioavailable.
Accordingly, it is an object of this invention to provide novel compounds of DL-alpha hydroxy analogs of methionine wherein the DL-alpha hydroxy analogs of methionine are in a form which can be readily absorbed after ingestion by animals and readily distributed and utilized in order to provide adequate methionine levels for proper health, growth, and dietary balance of the animals.
Another object of this invention is to provide a process for making novel compounds of DL-alpha hydroxy analogs of methionine which is simple to perform and can be economically utilized in large scale plant practice to prepare the novel compounds of this invention in bulk for ready utilization in large quantities to supplement the diets of animals and humans. The method of accomplishing these and other objects will become apparent from the following description of the invention.